SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7574d4b4ecd421cfc1ee4b1c1703b5b455c57f7475486866c53d1515862df362' 
  AND token = 'gTKUii6PWgKPcb6SxGaIaZxXTrrv0zhp8rLGbCXWns4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}